Jupiter's satellite Europa

Fig. 2.35 . Dark streaks mark Europa's smooth surface, forming a spidery, veined network in this Voyager 2 image taken on 9 July 1979. In contrast to Jupiter's satellite Callisto (see Figure 2.17), Europa has very few impact craters; the absence of craters suggests that the ice crust is relatively young. Internal stresses have apparently fractured Europa’s icy mantle, producing intersecting cracks that extend for thousands of kilometers but reach depths of less than 100 meters. The fractures may have been filled by liquid water gushing out from a global ocean in the satellite's interior, warmed by tidal heating. (Courtesy of NASA/JPL.)